The field of the invention is marine accessories, and the invention relates more particularly to accessories for preventing fuel from spilling into the water during refueling. Motorized marine craft typically employ one or more internally mounted fuel tanks to provide fuel for engines aboard such as a propulsion engine or engines, electrical generators, and the like. The filling of the fuel tank, or tanks, is accomplished through a filler neck which typically includes internal threads. A fuel cap is securely held by the threads and is typically provided with a gasket which prevents water from entering the fuel tank around the filler cap and fuel from escaping. Thus, unlike the typical automobile which has a vented filler cap, the typical marine craft has an unvented cap, and the vent for the fuel tank, or tanks, is provided through a separate vent line which has a fuel vent fitting outside of the hull below the sheer.
The fuel vent fitting of choice is fabricated from brass and chrome plated. It includes a blind vent passageway having external threads in the middle thereof and having a fuel hose fitting at one end and an enlarged vent portion with a cylindrical exterior wall and a pair of screened vent outlets which are directed downwardly so that they do not tend to take on any water.
When the fuel tank is being filled at a marine service station, the filler cap is removed from the fuel inlet line, and the filling nozzle inserted into the inlet line. During the filling process, the entering fuel drops to the level in the tank and in impacting the fuel in the tank develops a layer of foam. Because there is no way for the operator filling the tank to determine the level of the fuel, ultimately this foam is expelled through either the filler neck or the vent fitting, or both. The result is an unintentional overboard discharge onto the dock or into the waterway. In marine craft on a waterway, this creates a very serious pollution problem. Although current law prohibits the creation of a visible sheen on waterways, there is presently no way of absolutely preventing this indication of a fuel spill.